DIFFERENT EFFECTS OF CYCLIC-AMP AND BUTYRATE ON EOSINOPHILIC DIFFERENTIATION, APOPTOSIS AND BCL-2 EXPRESSION OF A HUMAN EOSINOPHILIC LEUKEMIA-CELL LINE, EOL-1

A human eosinophilic leukemia cell line, EoL-1, slopped proliferating at the G(1) phase, differentiated into eosinophilic granule-containing cells, and died by apoptosis when stimulated with dibutyryl cyclic AM P (dbcAMP). To clarify the effects of dbcAMP, the effects of butyrate and cAMP-increasing reagents, prostaglandin E-2 (PGE(2)) and forskolin , on EoL-1 cellular differentiation and apoptosis were examined and co mpared. PGE(2) and forskolin but not butyrate induced differentiation to eosinophilic granule-containing cells, suggesting that cAMP played a primary role in eosinophilic differentiation of EoL-1 cells, PGE(2), forskolin and butyrate, when used alone, did not induce apoptosis of EoL-1 cells significantly at the concentrations used, but sequential s timulation of EoL-1 cells with the cAMP-increasing reagents and butyra te showed that butyrate induced further maturation and apoptosis of cA MP-induced eosinophilic granule-containing cells, These results showed that cAMP and butyrate have different effects on eosinophilic differe ntiation and apoptosis of EoL-1 cells, The cAMP-increasing reagents an d butyrate also showed different effects on expression of members of t he bcl-2 family, PGE(2) decreased bcl-2 and bar levels, bcl-x(S) expre ssion. EoL-1 cells constitutively expressed Fas and anti-Fas antibody induced EoL-1 cell death, but the Fas/Fas ligand system was not involv ed in dbcAMP-induced EoL-1 cell apoptosis, The EoL-1 cell line is thus a useful model in which to examine differentiation and apoptosis of e osinophilic leukemia cells. (C) 1996 by John Wiley & Sons, Ltd.